Developing applications for ME

Hi all,

I'm quite new to all this ME stuff, but already have a - maybe basic - question. Suppose, you have a R/3 system with an industry solution running (e.g. retail) and want to leverage thos solutions specific fuinctionalities to your mobile devices out in the field. Does this mean complete new application development or is it something already existing made by SAP. If not, Do I have to code ABAP and Java, design tables, BAPIs and all that? Thanx for help

Volker